Historical Origins Exhibition at the WODCON: the Beijing-Hangzhou Grand Canal

Last section of the Grand Canal in Beijing.

Another impressive dredging accomplishment in ancient China is the well-known Beijing-Hangzhou Grand Canal. Of course this was also featured in the Historical Origins of Dredging in China exhibition at the latest instalment of the WODCON in Shanghai. During our visits to Shanghai1 and Beijing2, we’ve seen the canal at both ends, although they are an impressive 1797km apart.

Grand Canal exhibit in the Historical Origins exhibition at the WODCON.

Triggered by the sign board at the exhibition, I wanted to know more about this immense project. 2500 Years ago, the designation of Beijing as capital of China, was followed by an increase of the population. Any further expansion of the city was limited to the resources available nearby for supporting all these new citizens. The great rulers of ancient China, wanted to access the supplies of the south, where food and crops were abundant. It was decided to dig a canal, all the way from Hangzhou to Beijing3. The importance of the canal for the ancient Chinese civilisation is equivalent to what nowadays the Intracoastal Waterway means for the New York area. Although the ICW is an even longer waterway, it consists mostly of natural water bodies. This makes the Beijing-Hangzhou Grand Canal the longest dredged canal in the world.

Map of the various sections of the Grand Canal (Credit: Wikipedia).

The sign falsely boasts, that the Grand Canal is the oldest canal in the world. Sorry, that honour belongs to our ancient Egyptian engineers4. But the Chinese can be proud their canal is still in use today, whereas the Canal of the Pharaohs is now only used for irrigation. The Beijing-Hangzhou Grand Canal in China is therefore actively maintained. Partly even the traditional way: by hand.

Maintenance of the Grand Canal in the last section in Beijing.

After establishing the age and the length of the Grand Canal, there is another property that might be interesting: the width. I’ve seen sections varying between 10 and 50 meters. Probably the range is even more. Initially the width was depending on the local circumstances, requirements for navigation and possibly the limitations of manual labour.

Explanation on parameters for channel width determination.

Today, the width of a canal can be carefully engineered and a customer may require that the contractor delivers the width exactly. Therefore, it is necessary to know exactly what the capabilities of your cutter suction dredge are. Both at the lowest depth and at shallower depths for the slope of the sides. Knowing the geometry and the dimensions of the cutter suction dredge, one can calculate the reach with complicated trigonometry. Or one can build a model in the 3D environment of the design of the project and see what is possible5. There is also another clever solution to this problem. For every cutter suction dredge we designed, we developed a geometric scale model. It takes into account ladder depth, spud carriage length and swing angle. The result is the canal width that is possible for that cutter suction dredge. A further simple multiplication of canal width, cut height and channel length reveals the production volume. Either onboard or at the office, it provides a nice little instrument for production estimation.

Geometric scale model of a CSD650 for canal width calculation.

References

  1. WODCON, Damen
  2. Historical Origins Exhibition at the WODCON: Yu the Great, Discover Dredging
  3. Grand Canal (China), Wikipedia
  4. The Ancient History of the Cutter Suction Dredge ‘10th of Ramadan’, Discover Dredging
  5. Positioning and Survey System, Damen

See also

 

 

Historical Origins Exhibition at the WODCON: Yu the Great

Statue of a bronze Ox, commemorating Yu the Great.
Statue of a bronze Ox, commemorating Yu the Great.

Traveling all the way to the WODCON in Shanghai China1 presented an excellent opportunity to visit this wonderful country. So, after the congress, we travelled to Beijing, to visit the tourist highlights. However, as obsessed with dredging as I am, I can find inspiration for the stories on this website anywhere. Take for example this bronze ox. Quietly staring at the Summer Palace2, it might easily be overlooked by the innocent visitor. But it is very relevant for our dredging community. It is to commemorate the great Yu, who subdued the flood with the first dredging project in the world3.

Exhibit about Yu the Great at the historical origin show at the WODCON 2019.
Exhibit about Yu the Great at the historical origin show at the WODCON 2019.

Next to the interesting presentations and the conventional dredging exhibition, the WODCON organisation arranged a nice little exhibition on historic origins of dredging in China. Of course the first exhibit was about Yu. Intrigued by this little piece of information, I asked around and did some research on the internet to puzzle together, what the sign did not tell.

First of all, there are that many records4. It has been so long ago, there only remains oral tradition to consult. The facts are inconclusive, even claiming it is just a mythical tale. So, we will approach this Mythbuster style. Examine the myth and the facts. Test it. And if it does not provide the expected results, take it to the extreme. Unfortunately, we will not blow things up at this time. Maybe we will do that later on another topic.

Sign at the bronze ox at the Summer Palace, Beijing.
Sign at the bronze ox at the Summer Palace, Beijing.

The story depicted on the information sign is not completely in line with the historical data available. Let’s start with the ‘iron’ part of the ox. According to several sources, the adventures of the Great Yu may have happened 2000BCE. That is in the middle of the Stone Age5, at best early Bronze Age. Also, it was usually not ‘to ward of the floods’. Those were mitigated by a framework of dikes, dams and overflow weirs6. When an ox was mentioned, it is about protecting these civil works. But nowhere can I find a solid explanation about what an ox can do to protect a dike or how this procedure would contain the river in its human designed trajectory.

Water buffalo at the Li River, near Yangshuo.
Water buffalo at the Li River, near Yangshuo.

Even today, one can find bovine creatures standing in the river. And from a distance they might easily be mistaken for a field of boulders. Conversely, a field of boulders might also be mistaken for a herd of oxen…

Boulder field or rudimentary groyne in the Li River, near Yangshuo.
Boulder field (or rudimentary groyne?) in the Li River, near Yangshuo.

So, my hypothesis is: ‘the Great Yu constructed his dikes and protected them with groynes against erosion7. When the uninitiated had to describe what he constructed, they compared those with water buffalo and the oral tradition morphed this into iron oxen.’ This is only my opinion after just a little research and it is up to educated historians with their research to disprove it.

Discussing these civil works and the containment of rivers, made me think of my beloved home country through the famous Dutch poem ‘Memories of Holland’8.

Excellent masterpiece of hydraulic engineering to contain a river and example of modern groynes. (Credit: van den Herik-Sliedrecht).
Excellent masterpiece of hydraulic engineering to contain a river and example of modern groynes9. (Credit: van den Herik-Sliedrecht).

References

  1. WODCON, Damen
  2. Summer Palace, Wikipedia
  3. Great Flood (China), Wikipedia
  4. Yu the Great, Wikipedia
  5. History of China, Prehistory, Wikipedia
  6. Chinese Myth of the Deluge, China Heritage Quarterly
  7. Groyne, Wikipedia
  8. Herinnering aan Holland, David Reid Poetry Translation Prize
  9. Kribverlaging Waal Fase 3, Van den Herik-Sliedrecht

See also

My WODCON 2019 Presentation: Launching Robotic Dredging

Me, presenting my WODCON 2019 contribution.
Me, presenting my WODCON 2019 contribution.

Yesterday, I gave my presentation at the WODCON 2019 in Shanghai1. The WODCON is the triannual world dredging conference, were everybody in the dredging industry meets and exchanges knowledge and ideas. Just as I mentioned in my New Year’s post, I sometimes like to delve into some old archives, get inspiration and hatch new ideas2. So did I for this presentation.

Overview of the ‘Ketelmeer’ (Credit: Google Maps).
Overview of the ‘Ketelmeer’ (Credit: Google Maps).

A seminal dredging project concerning environmental dredging is the ‘Ketelmeer’ clean up dredging project, resulting in the creation of the contaminated sediment storage depot in the artificial island ‘IJsseloog’3. As careful removal of the contaminated sediment required novel dredging techniques, the government challenged the dredging industry to test four innovative concepts. The results were evaluated by the institute now called ‘Deltares’ and published in a report4. The original conclusion of the report was, that the auger dredge was the best in reducing the turbidity. Later, the bigger auger dredge ‘HAM291’ was constructed and used to actually clean up the lake. With the knowledge and the experience of the auger we also developed a range of auger attachments for our DOP pumps5.

Traditional auger attachment for a DOP pump excavator combination.
Traditional auger attachment for a DOP pump excavator combination.

Reading the Ketelmeer report again, it occurred to me, that one parameter had not been properly accounted for: the size of the dredge. The auger dredge was by far the smallest dredge in the game. With a weighed scoring method, the dredges were also compared in size and installed power. The reasoning is that a bigger dredge has more interaction with its environment. Naturally, the environment gets more disturbed and turbidity levels should be higher for a bigger dredge. And the data was there to support this hypothesis. Smaller is better! Still, this does not undermine the initial results of the concept, as that was evaluated for turbidity per cubic meter. The bigger dredges also delivered more production. But when comparing dredges of the same concept might the smaller ones will perform better on turbidity. And this is in accordance with our experience. Every project where we’ve supplied these auger dredge units, the contractor and the client where surprised and happy about the achieved turbidity levels. Now, we know why: smaller is less turbidity.

The next step in performance might be reached by further decreasing the size of the dredge. However, the DOP is already as small as it is for a viable application on an excavator. The conclusion is to have an auger operating directly on the bottom: an unmanned submarine dredging machine!

Possible general arrangement of a robotic dredge submarine.
Possible general arrangement of a robotic dredge submarine.

This machine should navigate by itself and self-supporting. The wear parts of the auger should be exchanged by itself and solar panels can provide extra energy for extended missions. It has only a small hopper and discharge should also be done quick and automatically. An unmanned barge or even a dump truck trailer at the shore of the waterway can be replaced at longer intervals. Obstacles and other tricky spots can be alerted to a human supervisor for later intervention. One machine alone does not have an impressive production. The real power is in applying them in numbers. As we are standing on the brink of a revolution in robotics and artificial intelligence, this scenario may be not as farfetched as from your first impression. Imagine a whole school of these mechanical fishes cleaning up your waterway, while you sleep…

Working method of robotic dredge submarine (Credit: Judith Korver).
Working method of robotic dredge submarine (Credit: Judith Korver).

References

  1. WODCON, Damen
  2. New Year’s post 2019, Discover Dredging
  3. Ketelmeer project, Wikipedia
  4. Rapportage baggerproeven Ketelmeer. RIZA Rapport, 97.023, ISBN 9036950708
  5. DOP Pumps, Damen

See also